Generally, a liquid crystal display (LCD) is provided with electrode terminals and wires. The terminals and wires include source, gate, and drain electrodes of thin film transistors (TFT's), which are used as switching devices within a liquid crystal cell. The terminals and wires also include data lines for applying a video data signal to each liquid crystal cell, gate lines for applying a scanning signal thereto, and pixel electrodes and common electrodes for coupling an electric field with a liquid crystal layer.
The electrode terminals and wires are made by depositing an electrode material on a substrate and then wet etching the material using a photoresist mask and patterning the same. The wet etching is performed by precipitating a substrate in an etchant liquid or by jetting the etchant liquid onto the substrate by an injection nozzle to react the etchant liquid with the electrode material.
FIG. 1 shows a structure of a conventional wet etching apparatus. The conventional wet etching apparatus includes a plurality of cassettes 20 within a loader 22, a first robot 26, a waiting part 24, an etching part 28, a tilt drain part 30, a de-ionized rinsing part 32, a second robot 36, and a spin drier 34.
The operation of the conventional apparatus is as follows. A substrate, formed with the photoresist mask pattern, is carried from one of the plurality of cassettes 20 into the waiting part 24 by the first robot 26 positioned within the loader 22. The substrate is then sent to the etching part 28 to carry out the etching.
The etching part 28 jets etchant liquid from an injection nozzle onto the substrate to etch the substrate by an etching reaction of an etching layer with the etchant liquid. Afterwards, the substrate is moved to the tilt drain part 30 which inclines the substrate at a desired angle to drain the etchant liquid left on the substrates. Then, any remaining etchant liquid left on the substrates is completely removed by rinsing with de-ionized water by the de-ionized rinsing part 32.
Thereafter, the second robot 36 carries the substrates from the de-ionized rinsing part 32 into the spin drier 34. The spin drier 34 dries the substrates, thus completing the wet etching process.
A process of forming the electrode terminals and the electrode lines on the substrate using the above-mentioned wet etching method is now described. First, the substrate is cleaned and then an electrode material is deposited on the substrate. Next, a mask pattern is formed on the electrode material layer as follows. Initially, a photoresist material is coated to cover the entire electrode material layer. Then the photoresist material is exposed to light to complete the mask pattern. After the mask pattern is formed, the substrate is carried into the wet etching apparatus as shown in FIG. 1 to perform the wet etching process. Thereafter, the mask pattern on the substrate is removed.
In the conventional process, however, an alien substance, such as a water mist or organic film, is often generated around the mask pattern during patterning. In other words, as shown in FIG. 2, an alien substance 42 may be left on the periphery of the mask pattern 40.
The alien substance 42 acts as an etching block interfering in the wet etching process and thus produces an unintended mask pattern as shown in FIG. 3. The shape of a non-etched portion 46 formed with the mask pattern 40 is not identical to the intended mask pattern. As a result, a shape corresponding to the unintended mask pattern remains after the etching process is complete.
In the conventional art, to prevent the generation of the unintended mask pattern, the alien substance 42 is eliminated by adding a cleaning process after formation of the mask pattern 40 and prior to the wet etching process. The alien substance 42 is eliminated by ashing using a separate wet etching apparatus or by cleaning using a separate ultraviolet equipment mounted with a low-pressure mercury lamp.
However, such conventional elimination process to remove alien substances is not performed during the photoresist formation process or the wet etching process, but is a separate process using different equipment. This requires additional resources and time. Further, it requires that the substrate be transported out of one set of equipment to another and then back. As such, productivity and quality are reduced.